Burglar alarm



FIG. 1 is a front, left perspective view of a burglar alarm showing my new design;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a front elevational view thereof; and,

FIG. 7 is a rear elevational view thereof.

The broken lines depict unclaimed environmental subject matter. 

The ornamental design for a burglar alarm, as shown and described. 